In a typical wireless communication system (e.g., mobile or cellular radio network), mobile user equipment units communicate via a radio access network to one or more core networks. The mobile user equipment units can be mobile stations such as mobile telephones (i.e., cellular telephones) and laptops, tablets, etc. with mobile termination, and thus can be, for example, portable, pocket, hand-held, computer-included, or car-mounted mobile devices which communicate voice and/or data with radio access network.
The radio access network covers a geographical area which is divided into cell areas, with each cell area being served by a base station of the wireless communication system. A cell is a geographical area where radio coverage is provided by the base station equipment at a base station site. Each cell is identified by a unique identity, which is broadcast in the cell. The radio base stations communicate over the air interface (e.g., radio frequency signal) with the user equipment units within range of the base stations. The antennas of the base stations receive the wireless “inputs” (e.g., radio frequency signal) and then filter out undesired noise and amplify the radio frequency signal. These amplifiers are sometimes referred to as low noise amplifiers (LNAs) and may be tower mounted amplifiers. Low noise may refer to the noise figure being less than an undesired level (e.g., as measured in decibels).
However, in order to enable reception of the radio frequency signal when there is problem with the amplifier, for instance because of a failure to supply power to the amplifier, there is often a bypass branch provided, which outputs a received radio frequency signal without amplification. This allows the base station to function even if the amplifier does not work. In this way, an operator can continue to provide (e.g., limited) service even though the amplifier does not function. The bypass branch thus can connect to the inputted radio frequency signal (e.g., from an antenna) in a so-called bypass mode.
Existing bypass solutions may require providing impedance (e.g., variable impedance) in the bypass branch to balance the impedance of the amplifier and/or providing two or more amplifiers to create a balanced amplifier module.
Existing bypass solutions may have a low noise amplifier and bypass path that impact each other, namely an (e.g., unused) port not having substantially full reflection and thus impacting other port(s). Further, in existing bypass solutions, in bypass mode, the amplifier input impedance is arbitrary, so the signal in the bypass path is arbitrary and at the same time, the amplifier is an active component so the bypass linearity is also limited by the amplifier path.